/**
 * Created by zhang_j on 2020/7/6
 */
public class 最长路径2 {

    public static int uniquePathsWithObstacles(int[][] obstacleGrid) {
        int m = obstacleGrid.length;
        if(m == 0){
            return 0;
        }
        int n = obstacleGrid[0].length;
        if(n == 0){
            return 0;
        }
        int[][] dp = new int[m][n];
        if(obstacleGrid[0][0] == 1){
            return 0;
        }
        dp[0][0] = 1;
        for(int i = 1;i < m;i++){
            if(obstacleGrid[i][0] == 1){
                dp[i][0] = 0;
                while(++i < m){
                    dp[i][0] = 0;
                }
                break;
            }
            dp[i][0] = 1;
        }
        for(int j = 1;j < n;j++){
            if(obstacleGrid[0][j] == 1){
                dp[0][j] = 0;
                while(++j < n){
                    dp[0][j] = 0;
                }
                break;
            }
            dp[0][j] = 1;
        }

        for(int i = 1;i < m;i++){
            for(int j = 1;j < n;j++){
                if(obstacleGrid[i][j] == 1){
                    dp[i][j] = 0;
                }else{
                    dp[i][j] = dp[i-1][j] + dp[i][j-1];
                }
            }
        }
        return dp[m-1][n-1];
    }
}
